PDTC115TK,115 Pre-Biased NPN Transistor Equivalent & Substitute Parts

Part Overview

The PDTC115TK,115 is a pre-biased NPN bipolar junction transistor manufactured by NXP USA Inc., designed for surface mount applications in the SOT-23-3 (SMT3) package. This component integrates an internal base resistor network to simplify circuit design and reduce component count in switching and logic applications.

The PDTC115TK,115 is classified as obsolete. Equivalent and substitute parts are necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements. Active alternatives with identical or compatible electrical characteristics are available from multiple manufacturers including Diodes Incorporated, Rohm Semiconductor, and Nexperia USA Inc.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN - Pre-Biased	—
Maximum Collector Current (Ic)	100	mA
Collector-Emitter Breakdown Voltage (Max)	50	V
Base Resistor (R1)	100	kOhms
DC Current Gain (hFE) @ Ic, Vce	100 @ 1mA, 5V	—
Vce Saturation (Max) @ Ib, Ic	150mV @ 250µA, 5mA	—
Collector Cutoff Current (Max)	1	µA
Maximum Power Dissipation	250	mW
Package / Case	TO-236-3, SC-59, SOT-23-3	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution eligibility for the PDTC115TK,115 is determined by the following critical parameters:

Mandatory Compatibility Criteria:

Transistor Type: NPN - Pre-Biased
Maximum Collector Current: 100 mA (minimum)
Collector-Emitter Breakdown Voltage: 50 V (minimum)
Base Resistor Configuration: 100 kOhms (R1)
DC Current Gain (hFE): 100 @ 1mA, 5V (minimum)
Vce Saturation: 150mV or lower @ 250µA, 5mA
Package Compatibility: SOT-23-3 or equivalent surface mount packages
RoHS3 Compliance: Required
MSL Rating: 1 (Unlimited)

Substitute Categories:

Category A - Direct Equivalents (SOT-23-3 Package, Identical Base Resistor): Parts with 100 kOhms base resistor, matching saturation characteristics, and SOT-23-3 packaging.

Category B - Functional Equivalents (SOT-23-3 Package, Alternative Base Resistor): Parts with different base resistor values (10 kOhms, 4.7 kOhms) but compatible electrical performance in SOT-23-3 package.

Category C - Package Variants (Alternative Surface Mount Packages): Parts with identical electrical specifications but different surface mount packages (SOT-323, SOT-523).

Category D - Higher Current Capability: Parts exceeding 100 mA collector current rating, suitable for applications requiring additional current margin.

Parameter Comparison

Part Number	Manufacturer	Ic (Max) mA	Vce(br) V	R1 kOhms	hFE @ 1mA, 5V	Vce Sat (Max) mV	Package	Status
PDTC115TK,115	NXP USA Inc.	100	50	100	100	150	SOT-23-3	Obsolete
DDTC115GCA-7-F	Diodes Incorporated	100	50	100	82 @ 5mA, 5V	300	SOT-23-3	Active
DDTC115GUA-7-F	Diodes Incorporated	100	50	100	82 @ 5mA, 5V	300	SOT-323	Active
DDTC115TE-7-F	Diodes Incorporated	100	50	100	100	300	SOT-523	Active
DTC114TKAT146	Rohm Semiconductor	100	50	10	100	300	SOT-23-3	Active
DTC115GKAT146	Rohm Semiconductor	100	50	100	82 @ 5mA, 5V	300	SOT-23-3	Not For New Designs
DTC115TKAT146	Rohm Semiconductor	100	50	100	100	300	SOT-23-3	Not For New Designs
DTC143TKAT146	Rohm Semiconductor	100	50	4.7	100	150	SOT-23-3	Active
DTD114GKT146	Rohm Semiconductor	500	50	10	56 @ 50mA, 5V	300	SOT-23-3	Active
PDTC115TT,215	Nexperia USA Inc.	100	50	100	100	150	SOT-23-3	Active

Engineering Selection Recommendations

Primary Recommendation for Direct Replacement:

PDTC115TT,215 (Nexperia USA Inc.) is the preferred direct substitute. This part maintains identical electrical specifications to the PDTC115TK,115, including 100 kOhms base resistor, 100 mA collector current, 50 V breakdown voltage, and 150 mV saturation voltage. The part is in active production status with ROHS3 compliance and unlimited moisture sensitivity rating. Inventory availability is confirmed at 6,839 pieces.

Secondary Recommendations (Active Status, SOT-23-3 Package):

DTC143TKAT146 (Rohm Semiconductor) provides an active alternative with identical saturation characteristics (150 mV @ 250µA, 5mA) and current gain specifications. The 4.7 kOhms base resistor provides faster switching response compared to the 100 kOhms configuration. This part is suitable for applications where reduced base drive time is beneficial. Inventory: 365,200 pieces.

DTC115TKAT146 (Rohm Semiconductor) offers electrical compatibility with 100 kOhms base resistor and 100 mA rating. However, this part is classified as "Not For New Designs" and should be used only for legacy system maintenance. Inventory: 60,300 pieces.

Alternative Package Options (Active Status):

DDTC115TE-7-F (Diodes Incorporated) in SOT-523 package provides identical base resistor value (100 kOhms) and current gain (100 @ 1mA, 5V) with active product status. This option is suitable for space-constrained applications. Inventory: 751 pieces.

DDTC115GUA-7-F (Diodes Incorporated) in SOT-323 package offers active status with 100 kOhms base resistor configuration. This package variant is appropriate for miniaturized designs. Inventory: 3,300 pieces.

Higher Current Applications:

DTD114GKT146 (Rohm Semiconductor) supports 500 mA collector current with 50 V breakdown voltage. This part is suitable only for applications requiring current capability exceeding 100 mA. The 10 kOhms base resistor and lower hFE (56 @ 50mA, 5V) require circuit redesign. Inventory: 6,300 pieces.

Compliance Status:

All recommended substitutes maintain ROHS3 compliance and unlimited moisture sensitivity rating (MSL 1), ensuring compatibility with current manufacturing and environmental standards.

Frequently Asked Questions (FAQ)

Q1: Can DDTC115GCA-7-F replace PDTC115TK,115 in existing designs?

DDTC115GCA-7-F is electrically compatible with identical 100 mA collector current, 50 V breakdown voltage, and 100 kOhms base resistor. However, the saturation voltage is specified at 300 mV compared to 150 mV for the original part. This higher saturation voltage may affect switching speed and power dissipation in applications with tight timing margins. Verification of circuit performance is required before implementation.

Q2: What is the difference between parts with 100 kOhms and 10 kOhms base resistors?

The base resistor value determines the input impedance and switching characteristics. A 100 kOhms resistor requires lower base current for saturation, reducing input drive requirements. A 10 kOhms resistor provides faster switching response but demands higher base current. Selection depends on circuit requirements for speed versus drive capability.

Q3: Are SOT-323 and SOT-523 packages pin-compatible with SOT-23-3?

No. SOT-323 and SOT-523 packages have different physical dimensions and pin configurations. PCB layout and footprint modifications are required for package substitution. Verify mechanical compatibility before design implementation.

Q4: Why is PDTC115TT,215 recommended over other Diodes Incorporated alternatives?

PDTC115TT,215 is manufactured by Nexperia USA Inc. (successor to NXP's discrete division) and provides the closest electrical match to the original PDTC115TK,115, including identical saturation voltage (150 mV) and base resistor value (100 kOhms). This minimizes circuit redesign requirements.

Q5: Can DTD114GKT146 be used as a drop-in replacement?

No. DTD114GKT146 is designed for higher current applications (500 mA versus 100 mA) and has different base resistor value (10 kOhms) and current gain characteristics. Circuit redesign is necessary to accommodate these differences. Use only when higher current capability is required.

Q6: What is the significance of "Not For New Designs" status?

Parts marked "Not For New Designs" are in production but manufacturers recommend against use in new circuit designs. These parts are suitable only for maintaining existing products or legacy system support. For new designs, select parts with "Active" status.

Q7: How do saturation voltage differences affect circuit performance?

Saturation voltage directly impacts power dissipation and switching speed. Lower saturation voltage (150 mV) reduces heat generation and improves efficiency. Higher saturation voltage (300 mV) increases power loss, particularly in high-frequency switching applications. Verify thermal and timing requirements before substitution.

Q8: Are all substitute parts RoHS3 compliant?

Yes. All recommended substitute parts listed maintain ROHS3 compliance and unlimited moisture sensitivity rating (MSL 1), ensuring compatibility with current manufacturing standards and environmental regulations.

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